Refer to FIG. 1, an exemplary diagram of antenna blockage. In this case, a ship 106 has an installed antenna 100. When the antenna 100 is transmitting or receiving above 0° (zero degrees) elevation (relative to the antenna 100), there are two exemplary blockages, blockage-a 102A and blockage-b 102B. Blockage-a 102A is located toward the stem and blockage-b 102B is toward the bow of the ship 106. Using the ship's bow as a reference for 0° (zero degrees) azimuth, blockage-a 102A has a blockage zone roughly from 165° to 195° azimuth and 0° to 15° elevation, and blockage-b 102B has a blockage zone roughly from 355° to 5° azimuth and 0° to 8° elevation. When the antenna 100 is pointing toward a blockage zone, the antenna may not be able to receive a desired signal, or reception may be highly degraded. Similarly, when the antenna 100 is pointing toward a blockage zone, transmission may not be successful due to interference from the blockage or for safety reasons (of people on board the ship), the antenna may not be allowed to transmit when facing a blockage zone.
Blockages are generally electromagnetically opaque structures. In the current non-limiting example of a ship, blockages include metal structures such as communication masts, funnels, and smokestacks. One or more blockages can result in one or more corresponding blockage zones hindering transmission and reception from and to an associated antenna.